<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <!-- 内部样式表 -->
    <style type="text/css">
        #div1{
            width: 400px;
            height: 400px;
            background-color: greenyellow;

            /* border 边框样式 */
            border-width: 1px; /*边框粗细*/
            border-style: dotted;  /* solid(实线) ，dotted:点状线 */
            border-color: blue;  /* 边框颜色 */

            /* 只用一个属性 */
            /*border: 4px double blue;*/
        }

        #div2{
            width: 150px;
            height: 150px;
            background-color: darkgoldenrod;
            margin: 100px;
            padding-top: 50px;
            padding-left: 50px;
        }

        #div3{
            width: 100px;
            height: 100px;
            background-color: green;
            /* 填充 */

        }

        #div4{
            width: 400px;
            height: 400px;
            background-color: greenyellow;
        }
    </style>
    <!--
          CSS盒子模型
          1.border 边框
          2.margin 间距
          3.padding 填充

    -->
</head>
<body>
    <div id="div1">
        <div id="div2">
            <div id="div3">&nbsp;</div>
        </div>
    </div>

    <div id="div4">&nbsp;</div>
</body>
</html>